In any criminal investigation it is important to ascertain the time the crime occurred. In the forensic science unit determining the time of the crime is determined in a novel manner of using the half life of radioactive material. While this is not the "usual" method, it it does allow students to determine time of the crime provided they know the initial and final conditions of the radioactive material. In this student activity students will learn about the concept of half life as it relates to radioactive material and graph the half life of various radioactive materials over time. In the Lord Vampire assessment task, they will use their understanding of radioactive half life to determine time of death.
Radioactive Decay of Element X
In this activity students will use a model of a radioactive element with a half life of 20 days to determine the behaviour of radioactive material. A box with about 160 squares (approximately 2 cm square for each piece) are shaken and dumped onto the table. Each square, which represents an atom, will have one side blank and the other marked in some manner (eg. striped). All the marked (striped) squares facing up will be removed and the process is repeated six times with the remaining squares. From this process, which is modelling the half life of the radioactive material, students will be able to graph the number of atoms verses time and begin to understand the behaviour of radioactive material.
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